This invention relates to a pen printer for converting data into printed form on a print sheet.
It has been proposed to convert data into printed form on a print sheet by employing a pen printer such, for example, as is disclosed in Japanese Patent Kokai No. 60-109845. As described therein, the pen printer includes a plurality of ink pens mounted as a unit on a pen carriage for printing figures with different colors. Each of the ink pens includes a pen tip secured on one end of a cantilever leaf spring and a pen actuator. The pen actuator includes a solenoid and a plunger coupled to the leaf spring for bringing the pen tip into pressure contact with the print sheet placed on a platen when the solenoid is energized. During a printing operation, the data are converted into electrical drive signals which are applied to cause the pen actuators to bring the respective pen tips selectively into pressure contact with the print sheet while reciprocating the pen carriage along the platen.
One problem in the prior art results from the fact that the pen actuators are positioned between the respective ink pens and the platen. This structure results in a severe limitation on the freedom of design of the path of the print sheet. Another problem in the prior art results from the fact that a plurality of ink pens are combined integrally in spite of the fact that the ink consumption is different from one color from another. This structure results in an economic penalty when the ink pens are thrown away due to ink shortage even though ink remains in some of the ink pens.